Specialist Softwashing
for Plymouth & Devon
That Cleans Without Damage
Restore your rendered walls, cladding and delicate exterior surfaces to their original finish — using low-pressure chemical cleaning that kills algae at the root, not just the surface. No pressure damage, no streaking, no shortcuts.
4.9★ rated · 109+ reviews · 9 years experience
What Is Softwashing?
Softwashing is a specialist cleaning method that uses low-pressure water combined with professional-grade biocidal solutions to clean exterior surfaces. Unlike traditional pressure washing, softwashing relies on chemistry rather than force — making it the only safe method for cleaning rendered walls, K-render, monocouche, pebble-dash, timber cladding and other surfaces that would be damaged by high pressure.
At Scrub & Shine Southwest, we provide softwashing services across Plymouth, Exeter, Torquay and the wider South West for both residential and commercial properties. Our team has extensive experience cleaning every type of exterior render and cladding system used on modern and traditional buildings.
The key advantage of softwashing is that it kills biological growth at the cellular level. Pressure washing only removes the visible surface layer of algae and moss — the root systems remain embedded in the render and regrow within weeks. Softwashing destroys the entire organism, meaning your walls stay cleaner for significantly longer.
Modern exterior render systems — including K-render, silicone render, monocouche and acrylic render — are designed to be self-cleaning through their textured surface. However, in the damp South West climate, algae growth overwhelms this self-cleaning ability within a few years. Softwashing restores the render's designed performance without compromising its surface integrity.
Why Pressure Washing Renders Is Risky
The single most common mistake homeowners make with rendered walls is pressure washing them. High-pressure water jets penetrate the render surface, driving moisture deep into the wall cavity. This trapped moisture causes efflorescence (white salt staining), internal damp patches and in severe cases can compromise the render's bond with the substrate.
K-render and monocouche renders have a deliberately textured surface that provides their colour and weather resistance. Pressure washing strips away this texture, leaving smooth, discoloured patches that cannot be repaired without full re-rendering. We see this damage regularly on properties across Plymouth where well-meaning owners or inexperienced cleaners have used the wrong method.
Even low-pressure washing applied too close or at the wrong angle can damage render. Water driven upward under laps and around window reveals finds paths into the wall structure. Once moisture is behind render, it can cause delamination — the render literally separates from the wall and bulges outward, eventually cracking and falling away.
Painted render is equally vulnerable. Pressure washing strips paint coatings, exposing the raw render beneath. This looks worse than the original algae staining and requires expensive repainting to rectify.
Algae growth on rendered walls isn't just ugly — it's actively damaging. Algae retains moisture against the render surface, promoting freeze-thaw damage in winter. The organic acids produced by algae and lichen chemically attack certain render types. The longer biological growth remains, the more permanent the staining becomes as organisms penetrate deeper into the surface.
Our Softwashing Process
Surface Assessment
We identify the render type, assess the severity of biological growth and check for any existing damage or areas requiring special attention before cleaning begins.
Protection & Preparation
Windows, doors, plants and surrounding surfaces are protected. Any areas of loose render or damaged pointing are noted and avoided during cleaning.
Biocide Application
Professional-grade biocidal solution is applied evenly across the wall surface using low-pressure spray equipment. The solution penetrates algae, moss and lichen colonies, killing organisms at root level.
Dwell & Rinse
The biocide is allowed to work for the appropriate dwell time before being gently rinsed away at low pressure. Stubborn areas receive targeted reapplication.
Post-Treatment & Review
A residual biocide treatment is applied that continues working over the following weeks, progressively cleaning any remaining discolouration. We photograph results and schedule a follow-up check if needed.
Advantages of Professional Softwashing
Zero Pressure Damage
Softwashing operates at a fraction of the pressure used in standard cleaning. Your render, cladding and paint coatings remain completely intact throughout the process.
Longer Lasting Results
Because softwashing kills biological growth at root level, results last 3–5 times longer than pressure washing. Your walls stay cleaner for years, not weeks.
Safe for All Renders
K-render, silicone render, monocouche, acrylic, lime render, pebble-dash and painted finishes are all safely cleaned without risk of surface damage or moisture penetration.
Restores Original Colour
Algae staining makes light-coloured renders look grey, green or black. Softwashing restores the original render colour without bleaching, stripping or repainting.
Prevents Structural Damage
Removing moisture-retaining biological growth protects render from freeze-thaw cracking, delamination and chemical erosion caused by organic acid production.
Increases Property Value
Clean, well-maintained rendered walls are a major contributor to kerb appeal. Properties with algae-stained walls routinely receive lower valuations from surveyors.
Softwashing: Render Types, Solutions & Technical Considerations
K-render (also known as K-Rend) is a silicone-based through-coloured render manufactured in Ireland and widely used across the UK since the early 2000s. K-render's textured surface is designed to be self-cleaning but is particularly susceptible to algae colonisation in damp climates like the South West. Our softwash solution for K-render uses a balanced biocide concentration that kills algae without affecting the silicone binder or pigments within the render.
Monocouche render is a single-coat, through-coloured cementitious render that's been a popular choice on new-build properties for the past 15 years. Monocouche has a slightly rougher texture than K-render and is more porous, meaning algae can establish more quickly. We adjust our biocide concentration and dwell times for monocouche to ensure thorough penetration without excessive saturation.
Traditional sand and cement render with a painted finish requires careful treatment. The paint coating is the waterproof barrier — any damage to the paint during cleaning will expose the porous cement render underneath. Our softwash approach preserves paint coatings while removing biological growth from the surface.
Pebble-dash (or rough-cast) render has a highly textured surface that traps debris and provides excellent purchase for algae growth. The irregular surface means softwashing is the only viable cleaning method — pressure washing simply cannot reach into the recesses between pebbles without damaging the exposed aggregate. Our application technique ensures biocide solution penetrates all surface irregularities.
Timber cladding — including both natural wood and composite board systems — requires specific biocide formulations that are safe for use on wood. Standard render softwash solutions can bleach or damage certain timber finishes. We carry dedicated wood-safe products for cladding cleaning.
The biocides we use are professional-grade quaternary ammonium compounds (QACs) that are effective against algae, moss, lichen and mould. These products are biodegradable and safe for use near plants when applied correctly. We take care to protect sensitive planting and rinse any overspray from vegetation immediately.
Following the primary clean, we apply a residual biocide that continues working over 4–8 weeks. Some staining — particularly from long-established red algae — fades progressively during this period. We schedule a follow-up check at 6–8 weeks to confirm full cleaning has been achieved and determine whether any touch-up treatment is needed.
Frequently Asked Questions
How much does softwashing cost in Plymouth?+
Typical residential softwashing costs £300–£600 depending on the size of the property and the extent of biological growth. A single-elevation clean (e.g. front-facing wall only) starts from around £150. We provide free quotes after assessing your property.
How long does softwashing take?+
Most residential properties take half a day for application. The biocide continues working for 4–8 weeks after application, progressively cleaning any remaining discolouration. The immediate visual improvement is typically 70–80%, reaching full results over the following weeks.
Is softwashing safe for K-render?+
Absolutely. Softwashing is the only recommended method for cleaning K-render. Pressure washing will damage the textured surface coating. Our softwash solutions are specifically formulated to be safe for silicone renders.
Will softwashing kill my plants?+
We take care to protect plants during application, including pre-wetting vegetation, using targeted spray patterns and rinsing any overspray immediately. The biocides we use are biodegradable. In 9 years, we've never caused plant damage.
How long do softwash results last?+
Typically 3–5 years depending on the render type, orientation and local conditions. North-facing walls in shaded positions will require retreatment sooner than south-facing walls in open positions.
Can you softwash a painted wall?+
Yes. Our softwash process is safe for painted render, masonry and timber. The low-pressure application preserves paint coatings while killing the biological growth on the surface.
Why not just pressure wash — isn't it faster?+
Pressure washing is faster but causes lasting damage to rendered surfaces and only removes surface growth. The moss and algae return within weeks because the root systems remain intact. Softwashing takes slightly longer but delivers results that last years, not weeks.
Do you softwash commercial buildings?+
Yes. We regularly softwash commercial premises, retail units, care homes and office buildings. We can work outside business hours to minimise disruption and offer scheduled maintenance contracts.
What if the render is already damaged?+
We assess all render condition before cleaning. If we identify areas of delamination, cracking or loose render, we'll advise you before proceeding. Softwashing damaged render may not be appropriate — we'll always be honest about what we can and can't achieve.
What areas do you cover for softwashing?+
We cover Plymouth, Exeter, Torquay, Liskeard, Bodmin, Newquay, Kingsbridge, Bude and surrounding areas. Call 07400 506955 for a free assessment.
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Contact us today for a free, no-obligation quote. We respond within 24 hours and can usually schedule your job within the week.
Fully insured · Free estimates · 9 years experience